1. Field of the Invention
The present invention relates to a motor lock determination device configured to perform a lock determination on an electric motor that drives an electric fan for cooling off refrigerant used in a cooling device provided in a vehicle.
2. Description of Related Art
Japanese Patent Application Publication No. 11-182244 (JP 11-182244 A) describes an electric fan device configured to control an electric motor that drives an electric fan for cooling off refrigerant for an air conditioner. In the electric fan device, when an over current flows to the electric motor, when an ambient temperature of the electric fan reaches a predetermined temperature or more than the predetermined temperature and the over current in the electric motor is eliminated, it is determined that the electric fan is locked due to freezing.
In the device of JP 11-182244 A, it is necessary to determine whether a current flowing, in the electric motor is an over current or not, in a lock determination on the electric fan, so that a current sensor for detecting the current flowing in the electric motor is required.
Further, when the lock determination is performed on the electric fan by use of a detection value of the current sensor as such, control software or a control circuit for controlling a flowing current to the electric motor according to the detection value of the current sensor is required in addition to the current sensor. In view of this, when the lock determination is performed on the electric fan by use of the detection value of the current sensor as such, there is such a disadvantage that it requires much cost.
On the other hand, such an electric fan device often includes an ambient temperature sensor and a refrigerant pressure sensor as standard, so as to adjust a refrigerant pressure appropriately. In view of this, it is desirable to perform a lock determination on the electric fan by use of the ambient temperature sensor and the refrigerant pressure sensor thus included as standard.